PROJECT NAME Polar_Crater_2 HIRISE SOURCE IMAGES PSP_009689_2645 PSP_010084_2645 TECHNICAL CONTACT INFORMATION NAME SARAH MATTSON INSTITUTION UNIVERSITY OF ARIZONA Products are tied to MOLA elevations. Elevation range for this project: VALID_MINIMUM = -3936.84 m VALID_MAXIMUM = -3857.74 m SOCET SET NGATE was used to extract terrain. Post spacing in DTM is 1 m. Notes: The 25cm orthoimages are of a subset of the DTM. The image stretch used for preprocessing these images was a non-linear stretch, meant to retain the range of very dark and very light values. The SCALING_FACTOR and OFFSET keywords in the orthoimage labels will not restore the pixel values to I/F in this case. KNOWN ARTIFACTS These are known artifacts present in some, but not all, HiRISE DTMs. They may not be present in this DTM! Look at the terrain shaded relief to detect these before using the DTM! - Boxes Some DTMs have square areas that are usually about .5-1 m different in elevation from the surrounding areas. These are artifacts of the processing algorithms used in Socet Set ((c) BAE Systems). There may be goups of these boxes. They are almost impossible to edit out, so the user should look for such artifacts in a terrain shaded relief map before using the DTM for analysis. - CCD seams A HiRISE image is made up of 10 individual images, stitched together along their long edges. In a DTM, these seams can be visible as long lines. These seams are difficult to remove from the whole - Faceted areas Areas that were very bland (low contrast) or deeply shadowed with low contrast and low signal may have a "faceted" look to them. Terrain in these areas is not trustworthy.